1. Functional Overview
23
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
1.1.4
PowerSpan II and PowerSpan Differences Summary
The following table summarizes the main PowerSpan II programmable features that were unavailable
in the PowerSpan device. All functional enhancements are programmable in order to make sure that all
original PowerSpan functionality can be exercised.
Table 2: PowerSpan II Functional Enhancements
Functional Enhancement Descriptions
See
Packaging Change
Packaging has been changed from HPBGA packages to HSBGA packages. Four variants are
available for PowerSpan II: two variants for the Single PCI
PowerSpan II and two variants for the Dual PCI PowerSpan II. Both the Single and Dual PCI
PowerSpan II have packages, signals, and pins that are backwards compatible with the original
PowerSpan device.
“Electrical and Signal
Characteristics” on
page 381
and
New Revision ID
PowerSpan II has a new ID.
“Register Descriptions”
on page 235
Read implementation
PowerSpan II supports 4 byte transactions.
True Little-endian Mode
A new endian mode was developed for PowerSpan II
Base Address Implementation
PowerSpan II supports a PCI base address of 0x00000.
“Register Descriptions”
on page 235
Maximum Retry Counter Modification
The maximum retry counter is programmable in PowerSpan II
“Register Descriptions”
on page 235
Arbitration Timing for Masters
PowerSpan II measures the length of time it takes a master to respond to the GNT# signal.
PowerPC 7400 Transaction Support
PowerSpan II has been designed to support specific PowerPC 7400 misaligned transactions.
“Processor Bus
Interface” on page 83
Delay Sampling of Transaction Start Signal
The PowerSpan II PB arbiter can be programmed to sample requests two clocks after the PB_TS_
signal is asserted.